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Senescence-associated secretory phenotype regulated by mTOR pathway in senescent cells
Maslyaeva, Sofya ; Ryšánek, David (advisor) ; Chrienová, Žofia (referee)
Senescence is a state of a cell characterized by permanent cell cycle arrest, growth of the cell, and other phenotypic changes, including proinflammatory secretome. Along with the beneficial aspects of senescence, it has an unfortunate outcome - it is a cause of age-related pathologies and tumor progression. Senecence-associated secretory phenotype (SASP) is responsible for that, as it alters the tissue microenvironment by the secretion of the inflammatory agents - chemokines, cytokines and other factors. Cellular senescence is linked to the activation of the mTOR (mechanistic target of rapamycin) nutrient- and mitogen-sensing pathway. Therefore, mTOR inhibition is a promising therapeutic strategy for the SASP suppression and of various types of cancer and age-related diseases. In this thesis I am going to summarize the current understanding of the mTOR's role in the mediation of SASP. Key words: Senescent cells, senescence-associated secretory phenotype, mTOR pathway, MTORC1
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Prevention of cellular aging in vitro
Kubovčák, Matej ; Černý, Jan (advisor) ; Ryšánek, David (referee)
This bachelor thesis explores foundational components of the aging process and their importance in cell culture systems. Signaling pathways controlling these processes are discussed, and several attractive targets were identified to be potentially developed as interventions. Aging is described within the evolutionary paradigm to provide a global framework for understanding the various aging processes and their explanation. Several models in nature were found to provide evidence that aging interventions can be successful and could therefore serve as a source of inspiration. Immunological context is provided to underline its importance in vivo, and the immune system-specific longevity mechanisms are elucidated for potential exploitation. Loss of cellular identity is identified as an essential detrimental factor in cell culture and is connected to the foundational aging mechanisms. This thesis can serve as a stepping stone for conducting research on better cultivation methodologies, thereby opening doors to technologies such as cultivated meat and bioartificial organs requiring unprecedented cell expansion. Keywords aging, aging reversal, cellular identity, in vitro cultures, stemness
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Biogeography, diversity and substrate specificity of aeroterrestrial green algal genus Klebsormidium (Streptophyta)
Ryšánek, David ; Škaloud, Pavel (advisor) ; Mareš, Jan (referee)
Filamentous aeroterestrial green algae genus Klebsormidium occurs in a very wide range of freshwater and terrestrial habitats. Recent results of molecular investigations led to the finding that the diversity within this genus is far greater than expected on the basis of the morphological features, and that the traditional phenotypic species concept is insufficient. I tried to differentiate phylogenetic lineages within the genus Klebsormidium by thein different biogeographical distribution and environmental preferences. Since no study dealing with the biogeographic pattern of aeroterrestrial algae was so far undertaken, another aim of this work was to test validity of the protist ubiquity model in aeroterrestrial habitats. I studied this issues based on the chloroplast rbcL molecular marker. Based on the obtained data I found that the geographic definition of particular Klebsormidium lineages turns out to be unusable because of the cosmopolitan occurrence of almost all genotypes. However, the data obtained from the substrate specificity study shows that clear ecological preferences exist within the genus Klebsormidium and could be simply used to define different lineages within the genus.
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Diversity and biogeography of protists
Ryšánek, David ; Škaloud, Pavel (advisor) ; Kulichová, Jana (referee)
My bachelor thesis consists of two parts. The first part is a literature review, the second part is a practical one, which contains the results of my own research. The first part of my thesis is devoted to the literature review, dealing with two current views on biodiversity and biogeography of protists. The first theory, model of protist ubiquity is described in a few points and illustrated by several examples. Likewise is presented the second hypothesis of moderate endemicity model. In conclusion, both models are compared and advantages and disadvantages of each theory are pointed out. In the second part of this thesis I briefly describe the genus Klebsormidium, which is followed by an optimization of molecular methods to study biodiversity and biogeography of this genus.
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Terestrické řasy rodu Klebsormidium (Streptophyta) ve světle hypotézy "Everything is everywhere, but the environment selects"
Ryšánek, David ; Škaloud, Pavel (advisor) ; Dvořák, Petr (referee) ; Leliaert, Frederik (referee)
In 1934, Baas Becking mentioned hypothesis "Everything is everywhere, but the environment selects", which still contains three current controversial issues in protists: (1) disunity in distribution patterns, (2) species concepts, and (3) the ecological preferences. In recent years, protistan biogeography and diversity has become a highly debated topic. Two opposite hypotheses have been proposed: the ubiquity model, which emphasizes the cosmopolitan distribution of protists with low global diversity; and the moderate endemicity model, which admits the existence of endemic species with limited distribution, leading to relatively high diversity. However, habitat preferences and ecological aspect to the distribution of species are rather missing in the discussion about geographic distribution. We examined terrestrial algal genus Klebsormidium (Streptophyta), which is one of the most abundant microautotrophs in various terrestrial and aerophytic habitats, and further (i) tested whether there is any biogeographical pattern of this microorganism, (ii) examined if there is a comparable diversity in the polar and temperate regions, (iii) investigated a potential role of ecological speciation processes on diversification, and (iv) clarified the taxonomic identity of Klebsormidium species. Our analyses...
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Biogeography, diversity and substrate specificity of aeroterrestrial green algal genus Klebsormidium (Streptophyta)
Ryšánek, David ; Škaloud, Pavel (advisor) ; Mareš, Jan (referee)
Filamentous aeroterestrial green algae genus Klebsormidium occurs in a very wide range of freshwater and terrestrial habitats. Recent results of molecular investigations led to the finding that the diversity within this genus is far greater than expected on the basis of the morphological features, and that the traditional phenotypic species concept is insufficient. I tried to differentiate phylogenetic lineages within the genus Klebsormidium by thein different biogeographical distribution and environmental preferences. Since no study dealing with the biogeographic pattern of aeroterrestrial algae was so far undertaken, another aim of this work was to test validity of the protist ubiquity model in aeroterrestrial habitats. I studied this issues based on the chloroplast rbcL molecular marker. Based on the obtained data I found that the geographic definition of particular Klebsormidium lineages turns out to be unusable because of the cosmopolitan occurrence of almost all genotypes. However, the data obtained from the substrate specificity study shows that clear ecological preferences exist within the genus Klebsormidium and could be simply used to define different lineages within the genus.
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Diversity and biogeography of protists
Ryšánek, David ; Kulichová, Jana (referee) ; Škaloud, Pavel (advisor)
My bachelor thesis consists of two parts. The first part is a literature review, the second part is a practical one, which contains the results of my own research. The first part of my thesis is devoted to the literature review, dealing with two current views on biodiversity and biogeography of protists. The first theory, model of protist ubiquity is described in a few points and illustrated by several examples. Likewise is presented the second hypothesis of moderate endemicity model. In conclusion, both models are compared and advantages and disadvantages of each theory are pointed out. In the second part of this thesis I briefly describe the genus Klebsormidium, which is followed by an optimization of molecular methods to study biodiversity and biogeography of this genus.
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